572 
MR.  R.  F.  TOMES  ON  THE  AFFINITIES 
[Nov.  1893, 
and  without  a  trace  of  interval  between  them  in  which  ccenenchyma 
could  exist.  There  are  neither  dissepiments,  tabulae,  nor  pseudo- 
synapticules  in  the  interseptal  loculi,  but  the  inside  of  the  corallites 
is  greatly  reduced  in  diameter  and  rendered  more  or  less  cylindrical 
by  the  deposition  of  an  excessive  quantity  of  stereoplasm,  which 
really  constitutes  a  great  deal  of  the  bulk  of  the  corallum,  and  makes 
it  solid  and  strong,  Xo  such  tissue,  however,  is  added  to  either  the 
septa  or  columella.  (See  PI.  XX.  fig.  3.) 
All  the  larger  septa  run  into  the  columella.  They  are  of  medium 
thickness,  straight,  and  without  any  kind  of  lateral  ornamentation. 
Astroccenia  decaphilla. 
Examples  of  this  species  from  the  Cretaceous  formation  at  Gosau, 
when  well  preserved,  have  the  thickened  wails  and  ornamental  cali- 
cular  surface  shown  in  the  figure  by  Eeuss  (‘  Beitrage,  etc./ 
Denkschr.  kais.  Akad.  Wissensch.  Wien,  vol.  vii.  1854,  pi.  viii.). 
If  figs.  5  and  6  of  pi.  viii.  in  his  work  be  examined,  it  will  be  seen 
that  the  calices  are  bounded  by  a  double  row  of  tubercles.  Between 
them  is  a  very  narrow  space,  the  position  of  the  true  wall.  Polished 
sections  do  not,  however,  add  much  to  our  knowledge  of  the  wall- 
structure.  The  rows  of  tubercles  are  really  the  ornamentation  of 
the  stereoplasm  ;  the  wall  itself,  represented  by  the  space  between 
them,  is  obviously  not  very  thick,  and  indeed  in  one  specimen  now 
before  me  there  is  an  extremely  fine  depressed  line  representing  the 
position  and  thickness  of  the  wall.  Another  specimen,  having  an 
approach  to  an  elevated  pyramidal  form,  shows  satisfactorily  the 
corallites  at  and  near  the  axis,  seen  in  section.  They  have  thin  and 
closely-applied  walls,  and  there  is  no  stereoplasm.  The  nearer  the 
corallites  are  to  the  outside  of  the  corallum,  the  more  are  they 
loaded  by  stereoplasm,  and  their  original  structure  hidden. 
Astroccenia  reticulata. 
Of  this  species  I  have  the  advantage  of  one  specimen  only  for 
examination,  but  it  is  a  very  instructive  one.  A  few  calices  had 
been  weathered  before  fossilization,  and  the  thickened  wall,  standing 
up  in  bold  relief,  has  a  central  thin  portion  which  is  still  more  promi¬ 
nent.  This  is  the  true  wall,  and  is  not  only  thiu,  but  in  some  places 
merely  rudimcntar}r. 
Astroccenia  ramosa. 
Transverse  sections  of  this  species  are  very  instructive,  for,  as  in 
A.  decaphylla ,  the  central  corallites  (those  which  are  more  or  less 
vertical  and  run  up  the  centre  of  the  corallum)  have  thin,  well-defined 
walls,  closely  applied  to  each  other,  and  not  in  the  least  obscured  by 
any  secondary  deposit.  The  outer  ones,  on  the  contrary,  are  very 
much  altered  by  such  an  addition,  and  the  walls  of  the  corallites  are 
with  difficulty  distinguished.  (See  PI.  XX.  fig.  5.) 
Astroccenia  tuberculata,  Beuss. 
Of  all  the  species  which  I  have  examined,  this  proves  the  least 
instructive.  The  corallum  seems  to  be  almost  wholly  made  up  of 
secondary  material ;  but,  as  I  have  no  section  showing  the  state  of 
